Search results for "flagella"
showing 10 items of 61 documents
PDZD7 connects the Usher protein complex to the intraflagellar transport machinery
2015
Several Usher syndrome (USH)-associated proteins are known to localize to the connecting cilium of photoreceptor cells. The unconventional myosin MYO7A (USH1B) was long accepted as the transport molecule responsible for the ciliary localization of USH proteins. However, based on the typical location of several of the USH proteins along the ciliary axoneme, the involvement of the main ciliary trafficking machinery, intraflagellar transport (IFT), seems apparent. The USH-associated scaffold protein PDZD7 is known to interact with SANS, Usherin, GPR98 and Whirlin, all of which can be found in the connecting cilium. Here, we report that PDZD7 provides the physical link of the USH-protein networ…
Protein Networks and Complexes in Photoreceptor Cilia
2007
Vertebrate photoreceptor cells are ciliated sensory cells specialized for single photon detection. The photoreceptor outer segment corresponds to the ciliary shaft of a prototypic cilium. In the outer segment compartment, the ciliary membrane is highly modified into membranous disks which are enveloped by the plasma membrane in rod cells. At these outer segment disks, the visual transduction cascade--a prototypical G-protein coupled receptor transduction pathway is arranged. The light sensitive outer segments are linked by the socalled connecting cilium with the inner segment, the photoreceptor compartment which contains all organelles necessary for cell metabolism. The connecting cilium co…
Unraveling the pleomorphic forms of Borrelia burgdorferi
2014
Borrelia burgdorferi bakteeri on puutiaisten välittämän borrelioosin taudinaiheuttaja. Tämä tavanomaisesti spirokeettana esiintyvä bakteeri kykenee vaihtamaan muotoaan ympäristöolosuhteiden muuttuessa epäsuotuisiksi. Borrelia-bakteerin eri esiintymismuotojen uskotaan olevan borrelioosin pitkittyneen taudinkuvan takana, minkä vuoksi näiden muotojen tutkiminen on tärkeää. Tämän pro gradu –työn tavoitteena oli tutkia B. burgdorferin pleomorfisia muotoja ja löytää muotoja erottavia morfologisia tekijöitä sekä eroja proteiiniekspressiossa ja borrelioosipotilasseerumivasteessa spirokeettojen ja pyöreän esiintymismuodon välillä. Olettamuksena oli, että konfokaalimikroskopialla muotojen väliltä löy…
Kif3a interacts with Dynactin subunit p150 Glued to organize centriole subdistal appendages.
2013
Formation of cilia, microtubule-based structures that function in propulsion and sensation, requires Kif3a, a subunit of Kinesin II essential for intraflagellar transport (IFT). We have found that, Kif3a is also required to organize centrioles. In the absence of Kif3a, the subdistal appendages of centrioles are disorganized and lack p150(Glued) and Ninein. Consequently, microtubule anchoring, centriole cohesion and basal foot formation are abrogated by loss of Kif3a. Kif3a localizes to the mother centriole and interacts with the Dynactin subunit p150(Glued) . Depletion of p150(Glued) phenocopies the effects of loss of Kif3a, indicating that Kif3a recruitment of p150(Glued) is critical for s…
The retinitis pigmentosa protein RP2 links pericentriolar vesicle transport between the Golgi and the primary cilium.
2010
Photoreceptors are complex ciliated sensory neurons. The basal body and periciliary ridge of photoreceptors function in association with the Golgi complex to regulate the export of proteins from the inner segment to the outer segment sensory axoneme. Here, we show that the retinitis pigmentosa protein RP2, which is a GTPase activating protein (GAP) for Arl3, localizes to the ciliary apparatus, namely the basal body and the associated centriole at the base of the photoreceptor cilium. Targeting to the ciliary base was dependent on N-terminal myristoylation. RP2 also localized to the Golgi and periciliary ridge of photoreceptors, which suggested a role for RP2 in regulating vesicle traffic an…
Hoeflea alexandrii sp. nov., isolated from the toxic dinoflagellate Alexandrium minutum AL1V
2006
A Gram-negative, aerobic, non-symbiotic bacterium (AM1V30(T)) was isolated from the toxic dinoflagellate Alexandrium minutum AL1V. On the basis of 16S rRNA gene sequence similarity, strain AM1V30(T) was most closely related (97.4 % similarity) to the type strain of Hoeflea marina, which belongs to the family Phyllobacteriaceae within the order Rhizobiales of the class Alphaproteobacteria. A polyphasic approach was used to clarify the taxonomic position of strain AM1V30(T). During the course of this study, a second species was described by others as belonging to the genus Hoeflea, namely Hoeflea phototrophica; it showed a somewhat higher level of 16S rRNA gene sequence similarity with respec…
LrhA as a new transcriptional key regulator of flagella, motility and chemotaxis genes in Escherichia coli
2002
The function of the LysR-type regulator LrhA of Escherichia coli was defined by comparing whole-genome mRNA profiles from wild-type E. coli and an isogenic lrhA mutant on a DNA microarray. In the lrhA mutant, a large number (48) of genes involved in flagellation, motility and chemotaxis showed relative mRNA abundances increased by factors between 3 and 80. When a representative set of five flagellar, motility and chemotaxis genes was tested in lacZ reporter gene fusions, similar factors for derepression were found in the lrhA mutant. In gel retardation experiments, the LrhA protein bound specifically to flhD and lrhA promoter DNA (apparent K-D approximate to 20 nM), whereas the promoters of…
Termite Gut Symbiotic Archaezoa Are Becoming Living Metabolic Fossils
2003
ABSTRACT Over the course of several million years, the eukaryotic gut symbionts of lower termites have become adapted to a cellulolytic environment. Up to now it has been believed that they produce nutriments using their own cellulolytic enzymes for the benefit of their termite host. However, we have now isolated two endoglucanases with similar apparent molecular masses of approximately 36 kDa from the not yet culturable symbiotic Archaezoa living in the hindgut of the most primitive Australian termite, Mastotermes darwiniensis . The N-terminal sequences of these cellulases exhibited significant homology to cellulases of termite origin, which belong to glycosyl hydrolase family 9. The corre…
Evolution of Early Metazoa: Phylogenetic Status of the Hexactinellida Within the Phylum of Porifera (Sponges)
1998
The evolution of the Metazoa from their protozoan ancestors is one of the greatest puzzles of phylogeny (Willmer 1994; Cavalier-Smith et al. 1996). The emergence of multicellular animals has been explained by two major theories: the syncytial theory (Hadzi 1963) - origin from a multinucleated ciliate - and the colonial theory (Haeckel 1868) - origin from a colonial flagellate - both of which assume a di(poly)phyletic origin of the Metazoa. Numerous attempts to resolve whether the Metazoa are of mono- or polyphyletic origin have sought evidence from a wide variety of developmental and morphological data such as body symmetry, type of development (protostome vs. deuterostome), type of body ca…
Ofd1, a Human Disease Gene, Regulates the Length and Distal Structure of Centrioles
2010
SUMMARYCentrosomes and their component centrioles represent the principal microtubule organizing centers of animal cells. Here we show that the gene underlying Orofaciodigital Syndrome 1, Ofd1, is a component of the distal centriole that controls centriole length. In the absence of Ofd1, distal regions of centrioles, but not procentrioles, elongate abnormally. These long centrioles are structurally similar to normal centrioles, but contain destabilized microtubules with abnormal post-translational modifications. Ofd1 is also important for centriole distal appendage formation and centriolar recruitment of the intraflagellar transport protein Ift88. To model OFD1 Syndrome in embryonic stem ce…